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Analýza morfometrických parametrů tracheid dřeva smrku ztepilého (Picea abies (L.) Karst.) na výzkumné ploše Bílý Kříž a Rájec-Němčice
Novák, Tomáš
This thesis is about analysis of morphometric parameters of Norway spruce tracheid wood from research areas Bílý Kříž and Rájec–Němčice. Wood for examining was sampled from different heights of trees. Width of the annual ring and percentage of late wood was determined at macroscopic level. Annual ring width ranged from 2,2 to 4,5 mm. The percentage of late wood was found to be 24 %. Microscopic analysis of tracheid wood dimensions followed. Radial size of tracheids was determined and averaged 31 μm. Tracheid cell wall thickness ranged from 2 to 10 μm. The number of tracheids increases with trunk height as does the width of the annual ring. Wood density of sampled wood averaged 450 kg·m-3. The variability of the wood structure by radius and height was examined. Subsequently, the obtained data was compared with precipitation and temperature.
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Influence of Wood Density on Measured Values when Working with a Kučera's Drill
Černý, Pavel
Diagnostics of wooden structures is still a widely used field in construction. The measured values during testing in wood diagnostics are always influenced by the properties of the wood. One of the most important roles in wood diagnostics is moisture, which affects a wide range of physical and mechanical properties. This was not the case when testing with the Kučera`s drill, which is standardly used for masonry diagnostics. For research purposes, the drill had to be transformed for use on wooden structures. The transformation was performed on the basis of a special reduction.
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Stanovení pružnostních a pevnostních charakteristik dřeva v čerstvém stavu
Bielesz, Robin
This thesis examines the elasticity and strength characteristics of freshly felled timber. Specifically, the wood of Norway maple (Acer platanoides L.). There was a whole trunk of one tree from urbanized environment, which were marked the world sides. After production of individual samples with dimension od 20 × 20 × 30 mm it has been necessary for each sample to describe his former position in the trunk (height, location in the trunk, location of the world side). The final experiment was performed on the testing machine Zwick 050, samples were tested by destructive method by pressure along the fibers. Then the results were processed using program testXpert from Zwick. The result is how to change the density, strength and elasticity characteristics in different locations in tree trunk.
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Průběh sušení dřevěných standardních zkušebních tělísek při konstantní teplotě v laboratorní sušárně
Kunstmüller, Robin
At the Department of Wood Science wooden test pieces with approximate dimensions of 2 × 2 × 3 centimetres are plentifully used for various tests and experiments in which it is often necessary to reduce humidity. Spruce, oak and beech are the most important woody plants in agriculture in the Czech Republic therefore this thesis deals with the drying of these species in a laboratory drying oven Incucell V 111 Standard, which is located at the Department of Wood Science. The goal of this work is to find out how long it takes for test pieces of chosen woody plants to reach zero percent humidity and to specify how the change of the moisture content of wood over time depends on the wood density. After the assessment of results, it was found out that spruce test pieces dry out the fastest, following by beech pieces and oak pieces dry out the slowest. It was managed to prove statistically significant the dependence of the change of the moisture content of wood over time on the wood density (with increasing density increases also drying time) for most models.
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Vliv defektů ve dřevě na stanovení rychlosti šíření zvuku ve dřevě v čerstvém stavu
Vobořil, Matěj
This bachelor research deals with determining the speed of sound propagation in wood in fresh state. Specifically, maple milk (Acer platanoides L.) was investigated. Acoustic properties were determined by the non-destructive method thanks device from Fakopp company. These were an ultrasonic timer and a microsecond timer. Sensors like SD02, TD45 and US10 were selected for measurement. The primary objective was to determine the velocity of the sound signal propagating both 1 m long trunk and the 20 x 20 x 300 mm sized samples and to determine the effect of wood defects on that velocity. The secondary objective was to determine the dependence of the measured results depending on the world side.
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Dynamika rozkladu tlejícího dřeva v přirozených temperátních lesích
Přívětivý, Tomáš
The decomposition dynamics of deadwood was investigated using robust 40-years-long temporal dataset and physical properties of decaying logs in alluvial, fir-beech and fir-spruce-beech natural forests. While the downed logs of most alluvial tree species are decomposed in 23-42 years depending on DBH, the large-sized logs of Quercus robur had a residence time 73 years. Deadwood of Fagus sylvatica decomposed completely in 30-53 years and Abies alba in 53-95 years depending on the macroclimatic conditions and DBH. Deadwood of Picea abies had a decomposition time 58-81 years on the site of a mountain mixed forest. In addition, the effect of the mortality mode and position of logs on the decomposition time was confirmed. Evaluation of deadwood density on sampled logs showed that the remaining mass (decay rate) varies greatly between the logs with the same values of time since death. This confirmed the need for robust data for observations about deadwood decomposition.
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Hodnocení vybraných elektrických vlhkoměrů při měření vlhkosti dřeva
Piňos, Pavel
This bachelor thesis focuses on detecting a range of humidity, in which selected electric hygrometers measure reliably and also an appropriateness of its use for measuring moisture of wood. The thesis is divided into two main parts which are a realization of the experiment and a statistic comparison and evaluation of measured data. The measuring of moisture was realized using four different types of hygrometers and then it was compared with the real (computed gravimetricaly) moisture of wood. The testing was realized on spruce samples. The next target was determining an effect of a density of wood on its real moisture. For demonstrating reliability of measuring moisture of selected hygrometers, samples were tested during five humidity conditions.
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